Extended Wear Ambulatory Electrocardiography And Physiological Sensor Monitor

ABSTRACT

Physiological monitoring can be provided through a wearable monitor that includes two components, a flexible extended wear electrode patch and a removable reusable monitor recorder. The wearable monitor sits centrally (in the midline) on the patient&#39;s chest along the sternum oriented top-to-bottom. The placement of the wearable monitor in a location at the sternal midline (or immediately to either side of the sternum) benefits extended wear by removing the requirement that ECG electrodes be continually placed in the same spots on the skin throughout the monitoring period. Instead, the patient can place an electrode patch anywhere within the general region of the sternum. Power is provided through a battery provided on the electrode patch, which avoids having to open the monitor recorder&#39;s housing for battery replacement.

CROSS-REFERENCE TO RELATED APPLICATION

This non-provisional patent application is a continuation of U.S. patentapplication Ser. No. 14/080,725, filed Nov. 14, 2013, pending, andfurther claims priority under 35 U.S.C. §119(e) to U.S. ProvisionalPatent application, Ser. No. 61/882,403, filed Sep. 25, 2013, the filingdates of which are claimed and the disclosures of which are incorporatedby reference.

FIELD

This application relates in general to electrocardiographic monitoringand, in particular, to an extended wear ambulatory electrocardiographyand physiological sensor monitor.

BACKGROUND

The heart emits electrical signals as a by-product of the propagation ofthe action potentials that trigger depolarization of heart fibers. Anelectrocardiogram (ECG) measures and records such electrical potentialsto visually depict the electrical activity of the heart over time.Conventionally, a standardized set format 12-lead configuration is usedby an ECG machine to record cardiac electrical signals fromwell-established traditional chest locations. Electrodes at the end ofeach lead are placed on the skin over the anterior thoracic region ofthe patient's body to the lower right and to the lower left of thesternum, on the left anterior chest, and on the limbs. Sensed cardiacelectrical activity is represented by PQRSTU waveforms that can beinterpreted post-ECG recordation to derive heart rate and physiology.The P-wave represents atrial electrical activity. The QRSTU componentsrepresent ventricular electrical activity.

An ECG is a tool used by physicians to diagnose heart problems and otherpotential health concerns. An ECG is a snapshot of heart function,typically recorded over 12 seconds, that can help diagnose rate andregularity of heartbeats, effect of drugs or cardiac devices, includingpacemakers and implantable cardioverter-defibrillators (ICDs), andwhether a patient has heart disease. ECGs are used in-clinic duringappointments, and, as a result, are limited to recording only thoseheart-related aspects present at the time of recording. Sporadicconditions that may not show up during a spot ECG recording requireother means to diagnose them. These disorders include fainting orsyncope; rhythm disorders, such as tachyarrhythmias andbradyarrhythmias; apneic episodes; and other cardiac and relateddisorders. Thus, an ECG only provides a partial picture and can beinsufficient for complete patient diagnosis of many cardiac disorders.

Diagnostic efficacy can be improved, when appropriate, through the useof long-term extended ECG monitoring. Recording sufficient ECG andrelated physiology over an extended period is challenging, and oftenessential to enabling a physician to identify events of potentialconcern. A 30-day observation day period is considered the “goldstandard” of ECG monitoring, yet achieving a 30-day observation dayperiod has proven unworkable because such ECG monitoring systems arearduous to employ, cumbersome to the patient, and excessively costly.Ambulatory monitoring in-clinic is implausible and impracticable.Nevertheless, if a patient's ECG could be recorded in an ambulatorysetting, thereby allowing the patient to engage in activities of dailyliving, the chances of acquiring meaningful information and capturing anabnormal event while the patient is engaged in normal activities becomesmore likely to be achieved.

For instance, the long-term wear of ECG electrodes is complicated byskin irritation and the inability ECG electrodes to maintain continualskin contact after a day or two. Moreover, time, dirt, moisture, andother environmental contaminants, as well as perspiration, skin oil, anddead skin cells from the patient's body, can get between an ECGelectrode, the non-conductive adhesive used to adhere the ECG electrode,and the skin's surface. All of these factors adversely affect electrodeadhesion and the quality of cardiac signal recordings. Furthermore, thephysical movements of the patient and their clothing impart variouscompressional, tensile, and torsional forces on the contact point of an

ECG electrode, especially over long recording times, and an inflexiblyfastened ECG electrode will be prone to becoming dislodged.Notwithstanding the cause of electrode dislodgment, depending upon thetype of ECG monitor employed, precise re-placement of a dislodged ECGelectrode maybe essential to ensuring signal capture at the samefidelity. Moreover, dislodgment may occur unbeknownst to the patient,making the ECG recordings worthless. Further, some patients may haveskin that is susceptible to itching or irritation, and the wearing ofECG electrodes can aggravate such skin conditions. Thus, a patient maywant or need to periodically remove or replace ECG electrodes during along-term ECG monitoring period, whether to replace a dislodgedelectrode, reestablish better adhesion, alleviate itching or irritation,allow for cleansing of the skin, allow for showering and exercise, orfor other purpose. Such replacement or slight alteration in electrodelocation actually facilitates the goal of recording the ECG signal forlong periods of time.

Conventionally, Holter monitors are widely used for long-term extendedECG monitoring. Typically, they are often used for only 24-48 hours. Atypical Holter monitor is a wearable and portable version of an ECG thatinclude cables for each electrode placed on the skin and a separatebattery-powered ECG recorder. The cable and electrode combination (orleads) are placed in the anterior thoracic region in a manner similar towhat is done with an in-clinic standard ECG machine. The duration of aHolter monitoring recording depends on the sensing and storagecapabilities of the monitor, as well as battery life. A “looping” Holtermonitor (or event) can operate for a longer period of time byoverwriting older ECG tracings, thence “recycling” storage in favor ofextended operation, yet at the risk of losing event data. Althoughcapable of extended ECG monitoring, Holter monitors are cumbersome,expensive and typically only available by medical prescription, whichlimits their usability. Further, the skill required to properly placethe electrodes on the patient's chest hinders or precludes a patientfrom replacing or removing the precordial leads and usually involvesmoving the patient from the physician office to a specialized centerwithin the hospital or clinic.

The ZIO XT Patch and ZIO Event Card devices, manufactured by iRhythmTech., Inc., San Francisco, Calif., are wearable stick-on monitoringdevices that are typically worn on the upper left pectoral region torespectively provide continuous and looping ECG recording. The locationis used to simulate surgically implanted monitors. Both of these devicesare prescription-only and for single patient use. The ZIO XT Patchdevice is limited to a 14-day monitoring period, while the electrodesonly of the ZIO Event Card device can be worn for up to 30 days. The ZIOXT Patch device combines both electronic recordation components,including battery, and physical electrodes into a unitary assembly thatadheres to the patient's skin. The ZIO XT Patch device uses adhesivesufficiently strong to support the weight of both the monitor and theelectrodes over an extended period of time and to resist disadherancefrom the patient's body, albeit at the cost of disallowing removal orrelocation during the monitoring period. Moreover, throughoutmonitoring, the battery is continually depleted and battery capacity canpotentially limit overall monitoring duration. The ZIO Event Card deviceis a form of downsized Holter monitor with a recorder component thatmust be removed temporarily during baths or other activities that coulddamage the non-waterproof electronics. Both devices representcompromises between length of wear and quality of ECG monitoring,especially with respect to ease of long term use, female-friendly fit,and quality of atrial (P-wave) signals.

Therefore, a need remains for an extended wear continuously recordingECG monitor practicably capable of being worn for a long period of timein both men and women and capable of recording atrial signals reliably.

A further need remains for a device capable of recording signals idealfor arrhythmia discrimination, especially a device designed for atrialactivity recording.

SUMMARY

Physiological monitoring can be provided through a wearable monitor thatincludes two components, a flexible extended wear electrode patch and aremovable reusable monitor recorder. The wearable monitor sits centrally(in the midline) on the patient's chest along the sternum orientedtop-to-bottom. The placement of the wearable monitor in a location atthe sternal midline (or immediately to either side of the sternum), withits unique narrow “hourglass”-like shape, benefits long-term extendedwear by removing the requirement that ECG electrodes be continuallyplaced in the same spots on the skin throughout the monitoring period.Instead, the patient is free to place an electrode patch anywhere withinthe general region of the sternum. In addition, power is providedthrough a battery provided on the electrode patch, which avoids havingto either periodically open the housing of the monitor recorder for thebattery replacement, which also creates the potential for moistureintrusion and human error, or to recharge the battery, which canpotentially take the monitor recorder off line for hours at a time. Inaddition, the electrode patch is intended to be disposable, while themonitor recorder is a reusable component. Thus, each time that theelectrode patch is replaced, a fresh battery is provided for the use ofthe monitor recorder.

One embodiment provides an extended wear electrocardiography andphysiological sensor monitor recorder that includes a sealed housingconfigured to be removably secured into a receptacle on an electrodepatch that has a battery electrically interfaced to a pair of electricalpads on the receptacle. The sealed housing also includes a set ofelectrical contacts that protrude from a bottom surface and correspondwith further electrical pads on the receptacle. Electronic circuitry isprovided within the sealed housing and includes a micro-controlleroperable to execute under micro-programmable control, an electrographicfront end circuit electrically interfaced to the micro-controller andoperable to sense electrocardiographic signals throughelectrocardiographic electrodes provided on the electrode patch, and aflash memory electrically interfaced with the micro-controller andoperable to store samples of the electrocardiographic signals.

A further embodiment provides an extended wear electrocardiography andphysiological sensor monitor that includes an electrode patch having aflexible backing formed of an elongated strip and a pair ofelectrocardiographic electrodes conductively exposed on a contactsurface of each end of the elongated strip. A receptacle is adhered toan outward-facing side of the elongated strip opposite the contactsurface and includes a plurality of electrical pads. A battery iselectrically interfaced to a pair of the electrical pads on thereceptacle. A flexible circuit is affixed on each end of the elongatedstrip and includes a pair of circuit traces electrically coupled to thepair of electrocardiographic electrodes and another pair of theelectrical pads. An electrocardiography monitor includes a sealedhousing configured to be removably secured into the receptacle on theelectrode patch and has a set of electrical contacts that protrude froma bottom surface and correspond with further electrical pads on thereceptacle. Electronic circuitry is provided within the sealed housingand includes a micro-controller operable to execute undermicro-programmable control, an electrographic front end circuitelectrically interfaced to the micro-controller and operable to senseelectrocardiographic signals through the electrocardiographic electrodesprovided on the electrode patch, and a flash memory electricallyinterfaced with the micro-controller and operable to store samples ofthe electrocardiographic signals.

The monitoring patch is especially suited to the female anatomy. Thenarrow longitudinal midsection can fit nicely within the intermammarycleft of the breasts without inducing discomfort, whereas conventionalpatch electrodes are wide and, if adhesed between the breasts, wouldcause chafing, irritation, frustration, and annoyance, leading to lowpatient compliance.

The foregoing aspects enhance ECG monitoring performance and qualityfacilitating long-term ECG recording, critical to accurate arrhythmiadiagnosis.

In addition, the foregoing aspects enhance comfort in women (and certainmen), but not irritation of the breasts, by placing the monitoring patchin the best location possible for optimizing the recording of cardiacsignals from the atrium, another feature critical to proper arrhythmiadiagnosis.

Still other embodiments will become readily apparent to those skilled inthe art from the following detailed description, wherein are describedembodiments by way of illustrating the best mode contemplated. As willbe realized, other and different embodiments are possible and theembodiments' several details are capable of modifications in variousobvious respects, all without departing from their spirit and the scope.Accordingly, the drawings and detailed description are to be regarded asillustrative in nature and not as restrictive.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 and 2 are diagrams showing, by way of examples, an extended wearelectrocardiography and physiological sensor monitor, including amonitor recorder in accordance with one embodiment, respectively fittedto the sternal region of a female patient and a male patient.

FIG. 3 is a perspective view showing an extended wear electrode patchwith a monitor recorder in accordance with one embodiment inserted.

FIG. 4 is a perspective view showing the monitor recorder of FIG. 3.

FIG. 5 is a perspective view showing the extended wear electrode patchof FIG. 3 without a monitor recorder inserted.

FIG. 6 is a bottom plan view of the monitor recorder of FIG. 3.

FIG. 7 is a top view showing the flexible circuit of the extended wearelectrode patch of FIG. 3 when mounted above the flexible backing.

FIG. 8 is a functional block diagram showing the component architectureof the circuitry of the monitor recorder of FIG. 3.

FIG. 9 is a functional block diagram showing the circuitry of theextended wear electrode patch of FIG. 3.

FIG. 10 is a flow diagram showing a monitor recorder-implemented methodfor monitoring ECG data for use in the monitor recorder of FIG. 3.

FIG. 11 is a graph showing, by way of example, a typical ECG waveform.

DETAILED DESCRIPTION

Physiological monitoring can be provided through a wearable monitor thatincludes two components, a flexible extended wear electrode patch and aremovable reusable monitor recorder. FIGS. 1 and 2 are diagrams showing,by way of examples, an extended wear electrocardiography andphysiological sensor monitor 12, including a monitor recorder 14 inaccordance with one embodiment, respectively fitted to the sternalregion of a female patient 10 and a male patient 11. The wearablemonitor 12 sits centrally (in the midline) on the patient's chest alongthe sternum 13 oriented top-to-bottom with the monitor recorder 14preferably situated towards the patient's head. In a further embodiment,the orientation of the wearable monitor 12 can be correctedpost-monitoring, as further described infra. The electrode patch 15 isshaped to fit comfortably and conformal to the contours of the patient'schest approximately centered on the sternal midline 16 (or immediatelyto either side of the sternum 13). The distal end of the electrode patch15 extends towards the Xiphoid process and, depending upon the patient'sbuild, may straddle the region over the Xiphoid process. The proximalend of the electrode patch 15, located under the monitor recorder 14, isbelow the manubrium and, depending upon patient's build, may straddlethe region over the manubrium.

The placement of the wearable monitor 12 in a location at the sternalmidline 16 (or immediately to either side of the sternum 13)significantly improves the ability of the wearable monitor 12 tocutaneously sense cardiac electric signals, particularly the P-wave (oratrial activity) and, to a lesser extent, the QRS interval signals inthe ECG waveforms that indicate ventricular activity. The sternum 13overlies the right atrium of the heart and the placement of the wearablemonitor 12 in the region of the sternal midline 13 puts the ECGelectrodes of the electrode patch 15 in a location better adapted tosensing and recording P-wave signals than other placement locations,say, the upper left pectoral region. In addition, placing the lower orinferior pole (ECG electrode) of the electrode patch 15 over (or near)the Xiphoid process facilitates sensing of right ventricular activityand provides superior recordation of the QRS interval.

During use, the electrode patch 15 is first adhesed to the skin alongthe sternal midline 16 (or immediately to either side of the sternum13). A monitor recorder 14 is then snapped into place on the electrodepatch 15 to initiate ECG monitoring. FIG. 3 is a perspective viewshowing an extended wear electrode patch 15 with a monitor recorder 14in accordance with one embodiment inserted. The body of the electrodepatch 15 is preferably constructed using a flexible backing 20 formed asan elongated strip 21 of wrap knit or similar stretchable material witha narrow longitudinal mid-section 23 evenly tapering inward from bothsides. A pair of cut-outs 22 between the distal and proximal ends of theelectrode patch 15 create a narrow longitudinal midsection 23 or“isthmus” and defines an elongated “hourglass”-like shape, when viewedfrom above.

The electrode patch 15 incorporates features that significantly improvewearability, performance, and patient comfort throughout an extendedmonitoring period. During wear, the electrode patch 15 is susceptible topushing, pulling, and torqueing movements, including compressional andtorsional forces when the patient bends forward, and tensile andtorsional forces when the patient leans backwards. To counter thesestress forces, the electrode patch 15 incorporates strain and crimpreliefs, such as described in commonly-assigned U.S. Patent, entitled“Extended Wear Electrocardiography Patch,” U.S. Pat. No. 9,545,204,issued on Jan. 17, 2017, the disclosure of which is incorporated byreference. In addition, the cut-outs 22 and longitudinal midsection 23help minimize interference with and discomfort to breast tissue,particularly in women (and gynecomastic men). The cut-outs 22 andlongitudinal midsection 23 further allow better conformity of theelectrode patch 15 to sternal bowing and to the narrow isthmus of flatskin that can occur along the bottom of the intermammary cleft betweenthe breasts, especially in buxom women. The cut-outs 22 and longitudinalmidsection 23 help the electrode patch 15 fit nicely between a pair offemale breasts in the intermammary cleft. Still other shapes, cut-outsand conformities to the electrode patch 15 are possible.

The monitor recorder 14 removably and reusably snaps into anelectrically non-conductive receptacle 25 during use. The monitorrecorder 14 contains electronic circuitry for recording and storing thepatient's electrocardiography as sensed via a pair of ECG electrodesprovided on the electrode patch 15, as further described infra beginningwith reference to FIG. 8. The non-conductive receptacle 25 is providedon the top surface of the flexible backing 20 with a retention catch 26and tension clip 27 molded into the non-conductive receptacle 25 toconformably receive and securely hold the monitor recorder 14 in place.

The monitor recorder 14 includes a sealed housing that snaps into placein the non-conductive receptacle 25. FIG. 4 is a perspective viewshowing the monitor recorder 14 of FIG. 3. The sealed housing 50 of themonitor recorder 14 intentionally has a rounded isoscelestrapezoidal-like shape 52, when viewed from above, such as described incommonly-assigned U.S. Design Patent, entitled “ElectrocardiographyMonitor,” U.S. Pat. No. D717,955, issued on Nov. 18, 2014, thedisclosure of which is incorporated by reference. The edges 51 along thetop and bottom surfaces are rounded for patient comfort. The sealedhousing 50 is approximately 47 mm long, 23 mm wide at the widest point,and 7 mm high, excluding a patient-operable tactile-feedback button 55.The sealed housing 50 can be molded out of polycarbonate, ABS, or analloy of those two materials. The button 55 is waterproof and thebutton's top outer surface is molded silicon rubber or similar softpliable material. A retention detent 53 and tension detent 54 are moldedalong the edges of the top surface of the housing 50 to respectivelyengage the retention catch 26 and the tension clip 27 molded intonon-conductive receptacle 25. Other shapes, features, and conformitiesof the sealed housing 50 are possible.

The electrode patch 15 is intended to be disposable. The monitorrecorder 14, however, is reusable and can be transferred to successiveelectrode patches 15 to ensure continuity of monitoring. The placementof the wearable monitor 12 in a location at the sternal midline 16 (orimmediately to either side of the sternum 13) benefits long-termextended wear by removing the requirement that ECG electrodes becontinually placed in the same spots on the skin throughout themonitoring period. Instead, the patient is free to place an electrodepatch 15 anywhere within the general region of the sternum 13.

As a result, at any point during ECG monitoring, the patient's skin isable to recover from the wearing of an electrode patch 15, whichincreases patient comfort and satisfaction, while the monitor recorder14 ensures ECG monitoring continuity with minimal effort. A monitorrecorder 14 is merely unsnapped from a worn out electrode patch 15, theworn out electrode patch 15 is removed from the skin, a new electrodepatch 15 is adhered to the skin, possibly in a new spot immediatelyadjacent to the earlier location, and the same monitor recorder 14 issnapped into the new electrode patch 15 to reinitiate and continue theECG monitoring.

During use, the electrode patch 15 is first adhered to the skin in thesternal region. FIG. 5 is a perspective view showing the extended wearelectrode patch 15 of FIG. 3 without a monitor recorder 14 inserted. Aflexible circuit 32 is adhered to each end of the flexible backing 20. Adistal circuit trace 33 and a proximal circuit trace (not shown)electrically couple ECG electrodes (not shown) to a pair of electricalpads 34. The electrical pads 34 are provided within a moisture-resistantseal 35 formed on the bottom surface of the non-conductive receptacle25. When the monitor recorder 14 is securely received into thenon-conductive receptacle 25, that is, snapped into place, theelectrical pads 34 interface to electrical contacts (not shown)protruding from the bottom surface of the monitor recorder 14, and themoisture-resistant seal 35 enables the monitor recorder 14 to be worn atall times, even during bathing or other activities that could expose themonitor recorder 14 to moisture.

In addition, a battery compartment 36 is formed on the bottom surface ofthe non-conductive receptacle 25, and a pair of battery leads (notshown) electrically interface the battery to another pair of theelectrical pads 34. The battery contained within the battery compartment35 can be replaceable, rechargeable or disposable.

The monitor recorder 14 draws power externally from the battery providedin the non-conductive receptacle 25, thereby uniquely obviating the needfor the monitor recorder 14 to carry a dedicated power source. FIG. 6 isa bottom plan view of the monitor recorder 14 of FIG. 3. A cavity 58 isformed on the bottom surface of the sealed housing 50 to accommodate theupward projection of the battery compartment 36 from the bottom surfaceof the non-conductive receptacle 25, when the monitor recorder 14 issecured in place on the non-conductive receptacle 25. A set ofelectrical contacts 56 protrude from the bottom surface of the sealedhousing 50 and are arranged in alignment with the electrical pads 34provided on the bottom surface of the non-conductive receptacle 25 toestablish electrical connections between the electrode patch 15 and themonitor recorder 14. In addition, a seal coupling 57 circumferentiallysurrounds the set of electrical contacts 56 and securely mates with themoisture-resistant seal 35 formed on the bottom surface of thenon-conductive receptacle 25.

The placement of the flexible backing 20 on the sternal midline 16 (orimmediately to either side of the sternum 13) also helps to minimize theside-to-side movement of the wearable monitor 12 in the left- andright-handed directions during wear. To counter the dislodgment of theflexible backing 20 due to compressional and torsional forces, a layerof non-irritating adhesive, such as hydrocolloid, is provided at leastpartially on the underside, or contact, surface of the flexible backing20, but only on the distal end 30 and the proximal end 31. As a result,the underside, or contact surface of the longitudinal midsection 23 doesnot have an adhesive layer and remains free to move relative to theskin. Thus, the longitudinal midsection 23 forms a crimp relief thatrespectively facilitates compression and twisting of the flexiblebacking 20 in response to compressional and torsional forces. Otherforms of flexible backing crimp reliefs are possible.

Unlike the flexible backing 20, the flexible circuit 32 is only able tobend and cannot stretch in a planar direction. The flexible circuit 32can be provided either above or below the flexible backing 20. FIG. 7 isa top view showing the flexible circuit 32 of the extended wearelectrode patch 15 of FIG. 3 when mounted above the flexible backing 20.A distal ECG electrode 38 and proximal ECG electrode 39 are respectivelycoupled to the distal and proximal ends of the flexible circuit 32. Astrain relief 40 is defined in the flexible circuit 32 at a locationthat is partially underneath the battery compartment 36 when theflexible circuit 32 is affixed to the flexible backing 20. The strainrelief 40 is laterally extendable to counter dislodgment of the ECGelectrodes 38, 39 due to tensile and torsional forces. A pair of strainrelief cutouts 41 partially extend transversely from each opposite sideof the flexible circuit 32 and continue longitudinally towards eachother to define in ‘S’-shaped pattern, when viewed from above. Thestrain relief respectively facilitates longitudinal extension andtwisting of the flexible circuit 32 in response to tensile and torsionalforces. Other forms of circuit board strain relief are possible.

ECG monitoring and other functions performed by the monitor recorder 14are provided through a micro controlled architecture. FIG. 8 is afunctional block diagram showing the component architecture of thecircuitry 60 of the monitor recorder 14 of FIG. 3. The circuitry 60 isexternally powered through a battery provided in the non-conductivereceptacle 25 (shown in FIG. 5). Both power and raw ECG signals, whichoriginate in the pair of ECG electrodes 38, 39 (shown in FIG. 7) on thedistal and proximal ends of the electrode patch 15, are received throughan external connector 65 that mates with a corresponding physicalconnector on the electrode patch 15. The external connector 65 includesthe set of electrical contacts 56 that protrude from the bottom surfaceof the sealed housing 50 and which physically and electrically interfacewith the set of pads 34 provided on the bottom surface of thenon-conductive receptacle 25. The external connector includes electricalcontacts 56 for data download, microcontroller communications, power,analog inputs, and a peripheral expansion port. The arrangement of thepins on the electrical connector 65 of the monitor recorder 14 and thedevice into which the monitor recorder 14 is attached, whether anelectrode patch 15 or download station (not shown), follow the sameelectrical pin assignment convention to facilitate interoperability. Theexternal connector 65 also serves as a physical interface to a downloadstation that permits the retrieval of stored ECG monitoring data,communication with the monitor recorder 14, and performance of otherfunctions.

Operation of the circuitry 60 of the monitor recorder 14 is managed by amicrocontroller 61. The micro-controller 61 includes a program memoryunit containing internal flash memory that is readable and writeable.The internal flash memory can also be programmed externally. Themicro-controller 61 draws power externally from the battery provided onthe electrode patch 15 via a pair of the electrical contacts 56. Themicrocontroller 61 connects to the ECG front end circuit 63 thatmeasures raw cutaneous electrical signals and generates an analog ECGsignal representative of the electrical activity of the patient's heartover time.

The circuitry 60 of the monitor recorder 14 also includes a flash memory62, which the micro-controller 61 uses for storing ECG monitoring dataand other physiology and information. The flash memory 62 also drawspower externally from the battery provided on the electrode patch 15 viaa pair of the electrical contacts 56. Data is stored in a serial flashmemory circuit, which supports read, erase and program operations over acommunications bus. The flash memory 62 enables the microcontroller 61to store digitized ECG data. The communications bus further enables theflash memory 62 to be directly accessed externally over the externalconnector 65 when the monitor recorder 14 is interfaced to a downloadstation.

The circuitry 60 of the monitor recorder 14 further includes anactigraphy sensor 64 implemented as a 3-axis accelerometer. Theaccelerometer may be configured to generate interrupt signals to themicrocontroller 61 by independent initial wake up and free fall events,as well as by device position. In addition, the actigraphy provided bythe accelerometer can be used during post-monitoring analysis to correctthe orientation of the monitor recorder 14 if, for instance, the monitorrecorder 14 has been inadvertently installed upside down, that is, withthe monitor recorder 14 oriented on the electrode patch 15 towards thepatient's feet, as well as for other event occurrence analyses.

The microcontroller 61 includes an expansion port that also utilizes thecommunications bus. External devices, separately drawing powerexternally from the battery provided on the electrode patch 15 or othersource, can interface to the microcontroller 61 over the expansion portin half duplex mode. For instance, an external physiology sensor can beprovided as part of the circuitry 60 of the monitor recorder 14, or canbe provided on the electrode patch 15 with communication with themicro-controller 61 provided over one of the electrical contacts 56. Thephysiology sensor can include an SpO₂ sensor, blood pressure sensor,temperature sensor, respiratory rate sensor, glucose sensor, airflowsensor, volumetric pressure sensing, or other types of sensor ortelemetric input sources. In a further embodiment, a wireless interfacefor interfacing with other wearable (or implantable) physiologymonitors, as well as data offload and programming, can be provided aspart of the circuitry 60 of the monitor recorder 14, or can be providedon the electrode patch 15 with communication with the micro-controller61 provided over one of the electrical contacts 56.

Finally, the circuitry 60 of the monitor recorder 14 includespatient-interfaceable components, including a tactile feedback button66, which a patient can press to mark events or to perform otherfunctions, and a buzzer 67, such as a speaker, magnetic resonator orpiezoelectric buzzer. The buzzer 67 can be used by the microcontroller61 to output feedback to a patient such as to confirm power up andinitiation of ECG monitoring. Still other components as part of thecircuitry 60 of the monitor recorder 14 are possible.

While the monitor recorder 14 operates under micro control, most of theelectrical components of the electrode patch 15 operate passively. FIG.9 is a functional block diagram showing the circuitry 70 of the extendedwear electrode patch 15 of FIG. 3. The circuitry 70 of the electrodepatch 15 is electrically coupled with the circuitry 60 of the monitorrecorder 14 through an external connector 74. The external connector 74is terminated through the set of pads 34 provided on the bottom of thenon-conductive receptacle 25, which electrically mate to correspondingelectrical contacts 56 protruding from the bottom surface of the sealedhousing 50 to electrically interface the monitor recorder 14 to theelectrode patch 15.

The circuitry 70 of the electrode patch 15 performs three primaryfunctions. First, a battery 71 is provided in a battery compartmentformed on the bottom surface of the non-conductive receptacle 25. Thebattery 71 is electrically interfaced to the circuitry 60 of the monitorrecorder 14 as a source of external power. The unique provisioning ofthe battery 71 on the electrode patch 15 provides several advantages.First, the locating of the battery 71 physically on the electrode patch15 lowers the center of gravity of the overall wearable monitor 12 andthereby helps to minimize shear forces and the effects of movements ofthe patient and clothing. Moreover, the housing 50 of the monitorrecorder 14 is sealed against moisture and providing power externallyavoids having to either periodically open the housing 50 for the batteryreplacement, which also creates the potential for moisture intrusion andhuman error, or to recharge the battery, which can potentially take themonitor recorder 14 off line for hours at a time. In addition, theelectrode patch 15 is intended to be disposable, while the monitorrecorder 14 is a reusable component. Each time that the electrode patch15 is replaced, a fresh battery is provided for the use of the monitorrecorder 14, which enhances ECG monitoring performance quality andduration of use. Finally, the architecture of the monitor recorder 14 isopen, in that other physiology sensors or components can be added byvirtue of the expansion port of the microcontroller 61. Requiring thoseadditional sensors or components to draw power from a source external tothe monitor recorder 14 keeps power considerations independent of themonitor recorder 14. Thus, a battery of higher capacity could beintroduced when needed to support the additional sensors or componentswithout effecting the monitor recorders circuitry 60.

Second, the pair of ECG electrodes 38, 39 respectively provided on thedistal and proximal ends of the flexible circuit 32 are electricallycoupled to the set of pads 34 provided on the bottom of thenon-conductive receptacle 25 by way of their respective circuit traces33, 37. The signal ECG electrode 39 includes a protection circuit 72,which is an inline resistor that protects the patient from excessiveleakage current.

Last, in a further embodiment, the circuitry 70 of the electrode patch15 includes a cryptographic circuit 73 to authenticate an electrodepatch 15 for use with a monitor recorder 14. The cryptographic circuit73 includes a device capable of secure authentication and validation.The cryptographic device 73 ensures that only genuine, non-expired,safe, and authenticated electrode patches 15 are permitted to providemonitoring data to a monitor recorder 14.

The monitor recorder 14 continuously monitors the patient's heart rateand physiology. FIG. 10 is a flow diagram showing a monitorrecorder-implemented method 100 for monitoring ECG data for use in themonitor recorder 14 of FIG. 3. Initially, upon being connected to theset of pads 34 provided with the non-conductive receptacle 25 when themonitor recorder 14 is snapped into place, the microcontroller 61executes a power up sequence (step 101). During the power up sequence,the voltage of the battery 71 is checked, the state of the flash memory62 is confirmed, both in terms of operability check and availablecapacity, and microcontroller operation is diagnostically confirmed. Ina further embodiment, an authentication procedure between themicrocontroller 61 and the electrode patch 15 are also performed.

Following satisfactory completion of the power up sequence, an iterativeprocessing loop (steps 102-109) is continually executed by themicrocontroller 61. During each iteration (step 102) of the processingloop, the ECG frontend 63 (shown in FIG. 8) continually senses thecutaneous ECG electrical signals (step 103) via the ECG electrodes 38,29 and is optimized to maintain the integrity of the P-wave. A sample ofthe ECG signal is read (step 104) by the microcontroller 61 by samplingthe analog ECG signal output front end 63. FIG. 11 is a graph showing,by way of example, a typical ECG waveform 110. The x-axis representstime in approximate units of tenths of a second. The y-axis representscutaneous electrical signal strength in approximate units of millivolts.The P-wave 111 has a smooth, normally upward, that is, positive,waveform that indicates atrial depolarization. The QRS complex usuallybegins with the downward deflection of a Q wave 112, followed by alarger upward deflection of an R-wave 113, and terminated with adownward waveform of the S wave 114, collectively representative ofventricular depolarization. The T wave 115 is normally a modest upwardwaveform, representative of ventricular depolarization, while the U wave116, often not directly observable, indicates the recovery period of thePurkinje conduction fibers.

Sampling of the R-to-R interval enables heart rate informationderivation. For instance, the R-to-R interval represents the ventricularrate and rhythm, while the P-to-P interval represents the atrial rateand rhythm. Importantly, the PR interval is indicative ofatrioventricular (AV) conduction time and abnormalities in the PRinterval can reveal underlying heart disorders, thus representinganother reason why the P-wave quality achievable by the extended wearambulatory electrocardiography and physiological sensor monitordescribed herein is medically unique and important. The long-termobservation of these ECG indicia, as provided through extended wear ofthe wearable monitor 12, provides valuable insights to the patient'scardiac function and overall well-being.

Each sampled ECG signal, in quantized and digitized form, is temporarilystaged in buffer (step 105), pending compression preparatory to storagein the flash memory 62 (step 106). Following compression, the compressedECG digitized sample is again buffered (step 107), then written to theflash memory 62 (step 108) using the communications bus. Processingcontinues (step 109), so long as the monitoring recorder 14 remainsconnected to the electrode patch 15 (and storage space remains availablein the flash memory 62), after which the processing loop is exited andexecution terminates. Still other operations and steps are possible.

While the invention has been particularly shown and described asreferenced to the embodiments thereof, those skilled in the art willunderstand that the foregoing and other changes in form and detail maybe made therein without departing from the spirit and scope.

What is claimed is:
 1. An extended wear electrocardiography andphysiological sensor monitor recorder, comprising: a sealed housingconfigured to be removably secured into a receptacle on an electrodepatch that comprises a battery electrically interfaced to a pair ofelectrical pads on the receptacle and comprising a set of electricalcontacts that protrude from a bottom surface and correspond with furtherelectrical pads on the receptacle; and electronic circuitry comprisedwithin the sealed housing, comprising: a micro-controller operable toexecute under micro-programmable control; an electrographic front endcircuit electrically interfaced to the micro-controller and operable tosense electrocardiographic signals through electrocardiographicelectrodes provided on the electrode patch; and a flash memoryelectrically interfaced with the micro-controller and operable to storesamples of the electrocardiographic signals.
 2. An electrocardiographyand physiological sensor monitor recorder according to claim 1, whereinthe housing is formed as a rounded isosceles trapezoidal shape.
 3. Anelectrocardiography and physiological sensor monitor recorder accordingto claim 1, comprising a tactile-feedback button on a top surface of thesealed housing.
 4. An electrocardiography and physiological sensormonitor recorder according to claim 1, wherein the micro-controllerexecutes a power up sequence during which the battery on the electrodepatch is checked, the state of the flash memory is confirmed, andoperation of the micro-controller is confirmed.
 5. Anelectrocardiography and physiological sensor monitor recorder accordingto claim 1, wherein the sealed housing is removed from the electrodepatch and removably secured into a further receptacle on a furtherelectrode patch.
 6. An electrocardiography and physiological sensormonitor recorder according to claim 1, the electrode patch furthercomprising: a flexible backing formed of an elongated strip ofstretchable material with a narrow longitudinal midsection and, on eachend, a contact surface at least partially coated with an adhesivedressing; a pair of the electrocardiographic electrodes conductivelyexposed on the contact surface of each end of the elongated strip; and aflexible circuit affixed on each end of the elongated strip andcomprising a pair of circuit traces electrically coupled to the pair ofthe electrocardiographic electrodes and a different pair of theelectrical pads.
 7. An electrocardiography and physiological sensormonitor recorder according to claim 1, further comprising: an expansionbus operatively interconnected to the micro-controller; a physiologysensor comprised within the electrode patch and operable to sensephysiology and to draw power from the battery via battery leads, thephysiology sensor electrically interfaced with the micro-controller overthe expansion bus; and the flash memory further operable through theexpansion bus to store samples of the physiology sensed by thephysiology sensor.
 8. An electrocardiography and physiological sensormonitor recorder according to claim 7, wherein the physiology sensor isselected from the group comprising an SpO₂ sensor, a blood pressuresensor, a temperature sensor, a respiratory rate sensor, a glucosesensor, an air flow sensor, and a volumetric pressure sensor.
 9. Anelectrocardiography and physiological sensor monitor recorder accordingto claim 1, further comprising: an expansion bus operativelyinterconnected to the micro-controller; a physiology sensor comprisedwithin the sealed housing and operable to sense physiology and to drawpower from the battery, the physiology sensor electrically interfacedwith the micro-controller over the expansion bus; and the flash memoryfurther operable through the expansion bus to store samples of thephysiology sensed by the physiology sensor.
 10. An electrocardiographyand physiological sensor monitor recorder according to claim 9, whereinthe physiology sensor is selected from the group comprising an SpO₂sensor, a blood pressure sensor, a temperature sensor, a respiratoryrate sensor, a glucose sensor, an air flow sensor, and a volumetricpressure sensor.
 11. An extended wear electrocardiography andphysiological sensor monitor, comprising: an electrode patch,comprising: a flexible backing formed of an elongated strip; a pair ofelectrocardiographic electrodes conductively exposed on a contactsurface of each end of the elongated strip; a receptacle adhered to anoutward-facing side of the elongated strip opposite the contact surfaceand comprising a plurality of electrical pads; a battery electricallyinterfaced to a pair of the electrical pads on the receptacle; and aflexible circuit affixed on each end of the elongated strip andcomprising a pair of circuit traces electrically coupled to the pair ofelectrocardiographic electrodes and another pair of the electrical pads;and an electrocardiography monitor having a sealed housing configured tobe removably secured into the receptacle on the electrode patch andcomprising: a set of electrical contacts that protrude from a bottomsurface and correspond with further electrical pads on the receptacle;and electronic circuitry comprised within the sealed housing,comprising: a micro-controller operable to execute undermicro-programmable control; an electrographic front end circuitelectrically interfaced to the micro-controller and operable to senseelectrocardiographic signals through the electrocardiographic electrodesprovided on the electrode patch; and a flash memory electricallyinterfaced with the micro-controller and operable to store samples ofthe electrocardiographic signals.
 12. An electrocardiography andphysiological sensor monitor according to claim 11, wherein the housingis formed as a rounded isosceles trapezoidal shape.
 13. Anelectrocardiography and physiological sensor monitor according to claim11, comprising a tactile-feedback button on a top surface of the sealedhousing.
 14. An electrocardiography and physiological sensor monitoraccording to claim 11, wherein the micro-controller executes a power upsequence during which the battery on the electrode patch is checked, thestate of the flash memory is confirmed, and operation of themicro-controller is confirmed.
 15. An electrocardiography andphysiological sensor monitor according to claim 11, wherein the sealedhousing is removed from the electrode patch and removably secured into afurther receptacle on a further electrode patch.
 16. Anelectrocardiography and physiological sensor monitor according to claim11, the electrode patch further comprising: a cryptographic circuit toauthenticate the electrode patch for use with the electrocardiographymonitor.
 17. An electrocardiography and physiological sensor monitoraccording to claim 11, further comprising: an expansion bus operativelyinterconnected to the micro-controller and electrically coupled to atleast one of the electrical pads; a physiology sensor comprised withinthe disposable extended wear electrode patch and operable to sensephysiology and to draw power from the battery via battery leads, thephysiology sensor electrically interfaced with the micro-controller overthe expansion bus; and the flash memory further operable through theexpansion bus to store samples of the physiology sensed by thephysiology sensor.
 18. An electrocardiography and physiological sensormonitor according to claim 17, wherein the physiology sensor is selectedfrom the group comprising an SpO₂ sensor, a blood pressure sensor, atemperature sensor, a respiratory rate sensor, a glucose sensor, an airflow sensor, and a volumetric pressure sensor.
 19. Anelectrocardiography and physiological sensor monitor according to claim11, further comprising: an expansion bus operatively interconnected tothe micro-controller; a physiology sensor comprised within theelectrocardiography monitor and operable to sense physiology and to drawpower from a battery via a pair of the electrical pads, the physiologysensor electrically interfaced with the micro-controller over theexpansion bus; and the flash memory further operable through theexpansion bus to store samples of the physiology sensed by thephysiology sensor.
 20. An electrocardiography and physiological sensormonitor according to claim 19, wherein the physiology sensor is selectedfrom the group comprising an SpO₂ sensor, a blood pressure sensor, atemperature sensor, a respiratory rate sensor, a glucose sensor, an airflow sensor, and a volumetric pressure sensor.